I agree with Grivooga. Ranking will make people feel inferior to others. I post on lots of other forums and see people jus post a random post just to get themselves to the next level.
However there is a good idea for rankings. For people that wants to have a higher rank they will have to post more which means that more people will be involved in the conversations that happens around here. So there is a good and bad side to rankings. I really don't care if there is a ranking or not.
Jeff Wong